An organic electroluminescent (hereinafter referred to as “organic EL”) light-emitting device, which is expected as a next-generation light-emitting device having low power consumption, can emit extensive colors of light originating from an organic light-emitting material and is formed of a self-light-emitting element, and thus, also receives attention as a display of a TV set or the like.
An organic EL element used in such an organic EL light-emitting device has a feature of being a thinner element compared with an inorganic EL element and being a surface light emitting element, and thus, applications for an illuminating apparatus, a backlight unit of a liquid crystal display, a light-emitting component for display decoration, digital signage, and the like which use these features are also expected. In particular, the thickness of an organic EL layer is several hundred nm, which is very thin, and thus, by forming a transparent support substrate and having a configuration in which light which passes through the transparent substrate can be taken out also from an opposite surface of the substrate, a transparent see-through type light-emitting element can be formed. Therefore, novel decoration and digital signage using an organic EL light-emitting device having a transparent see-through type light-emitting element mounted thereon are expected to be developed. Various kinds of advertisements including such display decoration, digital signage, and shop dressing are often relatively large, and thus, an organic EL light-emitting device used therein is desired to be larger accordingly. However, in reality, it is difficult to manufacture a large organic EL light-emitting device from the technological viewpoint and from the viewpoint of manufacturing cost. Therefore, together with development of a large organic EL light-emitting device, development of a method of manufacturing a large organic EL light-emitting device at low cost is required.
Methods of increasing the size of an organic EL light-emitting device conventionally include a method of increasing the size of the device by increasing the size of the substrate (mother glass) itself of the organic EL element. Methods of reducing costs include a method of increasing the number of the devices manufactured in one batch. However, an organic EL layer of an organic EL element is generally formed using vacuum deposition, and, as the size of the substrate increases, the manufacturing facilities using vacuum deposition becomes more expensive. Further, vacuum deposition has problems that it is technically difficult to uniformly form on a larger substrate an organic EL layer having a very small thickness of several hundred nm as the total thickness (inter-electrode distance), and in addition, as the substrate becomes larger, the use efficiency (yields) of a material becomes lower. Further, as described above, in an organic EL element used in an organic EL light-emitting device, the total thickness (inter-electrode distance) of an organic EL layer is several hundred nm, which is very small, and thus, extremely minute dust or the like is liable to cause a defect such as a short circuit. Therefore, there are problems that increase in number of the devices manufactured in one batch has a limit and the risk becomes higher as the size of the substrate increases.
It has been proposed to realize increasing the size of an organic EL light-emitting device not by increasing the size of a substrate itself of an organic EL element but by elongating a substrate of an organic EL element so as to have a fiber-like shape and arranging side by side a plurality of the fiber-like organic EL elements on a large base material, and to realize reduction in costs not by increasing the number of the devices manufactured in one batch but by using a roll-to-roll manufacturing process (see, for example, JP-A-2002-538502 and JP-A1-2005-122646).